


The Prisoner and the Professor

by Sirussly



Category: Harry Potter - J. K. Rowling
Genre: AU, Azkaban Remus, M/M, Marauders, Marauders' Era, Multi, Prisoner of Azkaban AU, Professor Sirius, The Prisoner of Azkaban, first wizarding war
Language: English
Status: In-Progress
Published: 2018-01-12
Updated: 2018-01-12
Packaged: 2019-03-03 21:58:03
Rating: General Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 1,323
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/13350348
Author URL: https://archiveofourown.org/users/Sirussly/pseuds/Sirussly
Summary: What if the Prisoner of Azkaban had been a different marauder?When James and Lily go in to hiding, Sirius is the obvious choice for secret keeper. But there are rumours of a spy within the Order, and Sirius Black has been disappearing for weeks at a time. So Remus Lupin is chosen instead.The events of a single night in the early days of war changes the course of history forever.





	The Prisoner and the Professor

This is what happened in the Shack in June:

Sirius found Harry's face first, wild and panicked behind his glasses, and though Remus was holding Ron's wand he did nothing except stare back. Sirius burned from the inside out. He felt like a loose thread of fabric where the harder you pulled, the less there was to stitch back into place. Remus wore his broken skin like an ill-fitted coat over the top of his bones and he was the same except not, not the same at all. Sirius met his eyes, one human and one something else, and he hated him.

“This is for my friends,” he said, and words of death tasted bitter on his tongue.

A portion of the wall crumbled to dust and Remus was back on his feet, disarming Sirius before the green light could fade from the corners of the room. The absence of a wand caused his hand to curl into a tight fist, and Sirius used it to beat the werewolf to the ground.

“YOU–KILLED–THEM–”

“Sirius _listen_ –”

“YOU KILLED JAMES AND LILY AND NOW YOU WANT THEIR SON, TOO?”

“I would never touch Harry, you don't–”

“I SAW YOUR NAME ON THE MAP, LUPIN!”

“ _Then you should have seen Peter's, too!”_

For a moment Sirius froze and thought perhaps the blood between Remus' teeth had marred his words, but then Remus threw a punch of his own and everything turned white.

When his vision returned Remus was still speaking, and there was that name again, _Peter_ , but Sirius could do nothing but crouch awkwardly on the rotten floorboards, breathe, stare at the rat struggling madly in Ron's grip, breathe, remember the spy, his brother, a broken pair of glasses, breathe–

“We switched the secret keeper,” Remus said, and something inside Sirius broke a little.

Remus was staring at him and Sirius knew a part of it meant he hated him and that a part of him hated Remus in return – because it wasn't just a switch you could turn off, not after twelve years, not after five words.

But then Remus held his hand out to him and Sirius saw the tattoos, black life-lines that ran from his wrists, along the length of his arms and curve of his shoulders until they disappeared into the hair at his jawline. They were seams, holding together animal and man in two halves of the same body. Sirius took the hand, allowed himself to be pulled up. When they embraced each other he felt the seams come apart slightly, started hating Remus a little less and himself a little more.

Then the rat.

“Professor...” Hermione spoke, voice shaking. “Did– did he say... Peter Pettigrew is alive?”

He felt his insides go cold, no longer burning at all, and then Ron shrieked and the rat was suddenly in his grip and Sirius was squeezing–

Remus was beside him and he smelled of death. _“Stop.”_ It was a command, not a plea.

Sirius watched as the rat's tiny black eyes popped, its squeals cut short as the air stopped flowing. Remus made a noise, terrible and predatory, and long nails pressed into Sirius' arm.

“I've waited... twelve years...”

His orange eye shone and Sirius saw the flash of canines, wondered if there was anything left of Remus after all. Swallowing his disgust he let the rat breathe again, feeling its heart beat wildly in his palm. He pointed his wand at the traitor in his grip.

“Together?”

Remus nodded, wet his lips with his tongue. “I think so.”

There was a crack and a flash of light and the hailed martyr crumpled at their feet, trying in vain scramble away on hands and knees that were too slow, too human. Sirius noticed how the skin was stretched too-tightly over his clawed fingers, watched it twitch and shudder, and thinking quickly – flicked his wand. The man froze as a faint shimmer settled over him. “No more running away, Wormtail,” Sirius hissed through clenched teeth.

Remus stepped in front of the whimpering man and crouched, their faces inches apart. “Secret Keeper,” he breathed.

Watching them both, hearing the words, more pieces of Sirius broke inside him. The feeling was so like that last night in October, only Sirius had thought there was nothing whole left of him to shatter since then. The rat who was now not a rat babbled endlessly until Remus silenced him.

“Do you know what tonight is?” he said, so softly that Sirius struggled to hear him. “Look outside.”

Sirius did, and so did the not-rat, and it was the first time in twelve years that Sirius had forgotten about the moon.

“We don't have very long,” Remus spoke, unblinking. “And then I'm going to eat you.”

Peter began to cry.

“You can't– it's still me, Remus, I'm still your friend... ” His voice was exactly the same and it startled Sirius for a moment, to hear a boy's high, frightened voice come from a balding man.

“Harry...” Sirius said, the name laced with more fear than he had felt in a long time, “Ron, Hermione – get out of here.”

“But Sirius– ”

“Do as I say. Quickly.”

“You can't kill him,” Harry spoke, and he was looking at Remus. “You can't.”

Remus' animal stare flickered then, over towards the boy with eyes too old for his face, staring back at him from behind a pair of cracked glasses. “This is the man who sold your parents to Voldemort, Harry,” he said, bared teeth still inches away from Peter, who was whimpering in quiet relief. “He is the reason they are dead.”

“I know,” Harry replied, his hands shaking. “But I don't reckon my Dad would've wanted you to become a murderer for him.”

Sirius saw the wolf falter, just a little.

“Oh Harry, kind boy – sweet boy– ” Peter wheezed. “You understand, I knew you would – I had no choice, I did it to save you, to save everyone...”

Remus stood then, taking Peter with him by the throat. He dangled in his grip, choking, toes inches above the dusty floor.

“You saved. No-one. Except yourself.”

Sirius saw the tendons in Remus' arm move like eels beneath his skin, his scars standing out vividly, glowing faintly in the changing light. “Let me take him back to the castle” Sirius pleaded, “I'll tie him up, Remus, just let me– ”

“You... should leave now...” Remus spoke, hoarse with pain and no longer human, and Sirius wondered at what point the man had fled the body.

Panic swallowed Sirius whole, and he grabbed his godson tightly by the wrist. “Everybody out of here,” he ordered, sounding nothing like a professor, “...right now, before he– ”

There was an almighty crack as Remus' back broke in two.

Hermione screamed and Sirius felt his heart stop – he grabbed them all, dragging them towards the door. Something that had looked like Remus seconds ago but most certainly wasn't roared at them, sounding like every nightmare Sirius had ever had at once. The world tilted, panic choking the air from his lungs as he pushed the children ahead of him and they tumbled out of the door. “GO!” he shouted. “GO, I'LL BE RIGHT BEHIND– ”

And then Severus Snape was in the doorway, staring at him with black eyes. He said nothing and slammed the door shut.

Sirius could Harry screaming on the other side of the locked door, heard Peter screaming behind him, suffocated by his useless human body, and the half-thing was screaming too, an inhuman noise that made every hair on Sirius' body stand rigid.

“ _Sirius, let me change back, he'll tear me apart, Sirius–!”_ Peter was hysterical, attempting to squeeze himself behind a broken bookcase as Sirius stood numb between him and the thing on the floor. Then the thing stopped screaming, and looked at them both.

This is what happened in the Shack in June.

And this is what happened before. 

**Author's Note:**

> This began as a [hastily-written drabble](https://sirussly.tumblr.com/post/168654079535/what-if-the-prisoner-of-azkaban-had-been-a) and turned into... this. I am in the throes of plotting everything that happened before this point, and hope to update with with further chapters as I go.
> 
> Part of this prologue was made into an rp thread by myself and TT [here](https://sirussly.tumblr.com/post/168763872691/the-prisoner-and-the-professor), if you'd like to see.
> 
> Continual gratitude to TT and Meg who patiently beta everything I throw at them in the early hours of the morning <3


End file.
